Polarizing plates are widely used as an element for supplying polarization and an element for detecting polarization in a liquid crystal display. As such polarizing plates, those obtained by adhering a protective film composed of triacetylcellulose to a polarizing film composed of a polyvinyl alcohol resin are conventionally used, and thinning and weight reduction are recently required with development to mobile instruments such as note book type personal computers, cellular telephones and the like as liquid crystal displays, further, development to large size televisions and the like.
As a method of producing such a thin type polarizing plate, there is suggested a method in which a solution containing a polyvinyl alcohol resin is coated on the surface of a base material film to provide a resin layer, then, it is stretched and then colored to obtain a polarizing layered film having a polarizer layer, and this is utilized as it is as a polarizing plate, or a protective film is pasted on the film, then, the base material film is peeled to give a layered which is utilized as a polarizing plate (see, e.g., JP 2000-338329-A, JP 2009-93074-A, JP 2009-98653-A and JP 2003-43257-A).
In the above-described conventional method, however, a phenomenon sometimes occurs in which both ends of a base material film warp toward a resin layer side composed of a polyvinyl alcohol resin in a drying step after coating a solution containing the polyvinyl alcohol resin on the surface of the base film and the like, and if the film is allowed to flow continuously under this condition as it is, a trouble of folding the end of the film toward the inner side in a drying furnace or at an exit of a drying furnace is sometimes caused in due course.
Then, the present invention has an object of providing a method of producing a layered film or a polarizing plate with good productivity while preventing the above-described warping phenomenon.